Richard Desmond, proprietor of Express Newspapers, became caught up in a pornographic telephone and internet scam which ended with him receiving death threats from the mafia, according to documents emerging from a racketeering court case in New York.

Court papers suggest that a deal, whereby companies which later turned out to be mafia-linked, placed advertisements in Mr Desmond's top-shelf magazines in Britain went so badly wrong that a "soldier" from the Gambino crime family flew to London to issue a warning to Mr Desmond - only to be told by the publisher that he was "stupid" and "common".

The documents allege that soon after the meeting, according to the FBI's sources, a senior executive at Mr Desmond's publishing group, Northern and Shell, was pistol-whipped and had a Taser-style gun applied to his testicles while on trip to New York.